Stilt walking, bipedal movement by creature noticed

From depictions in ancient art to cartoons and animations, the octopus has long been characterised as a monster of the deep, with long and powerful arms capable of grabbing ships and devouring men. Though a few species among them are poisonous, the majority are small and intelligent and have evolved their own mechanism of self-defence. Modern research has revealed that these tentacled creatures are the most intelligent group among invertebrates.

Researchers at the Department of Aquatic Biology and Fisheries, University of Kerala, have now recorded the ‘tool-use behaviour’ of octopuses in captivity as evidence of their advanced cognitive ability. A research article published in the Journal of Threatened Taxa highlights the use of coconut shell by the veined octopus ( Amphioctopus marginatus ) collected from the Kerala coast and kept in an aquarium.

Observations recorded by the researchers, V. Sreeja and A. Biju Kumar, recorded the use of coconut shells kept in the aquarium as portable armour, protective shelter and home by the octopus. The paper says it manoeuvred the two coconut shell pieces to make a home and resided within it. The researchers recorded the breeding of the veined octopus in coconut shells. A female specimen also selected a coconut shell for laying eggs. By continuously sweeping its arms and squirting jets of water, the octopus kept off particles of debris and microorganisms from aggregating on the eggs.

Observations on the locomotive patterns of A marginatus in captivity showed stilt walking in which the arms were used as rigid limbs and bipedal movement in which two arms are used for locomotion and the remaining six arms to provide camouflage. According to Dr. Kumar, Associate Professor and Head of the department, these movements are different from the normal crawling which involves several arms sprawling around the body.